N = int(input())
s = str(N // (10**9 + 1))
n = [None] + [9, 9, 90, 90, 900, 900, 9000, 9000, 90000, 900000]
ketasuu = len(s)
ans = sum(n[1:ketasuu])
add = 1

if ketasuu % 2 == 0:
    l = list(map(int, s[:ketasuu//2]))
    r = list(map(int, s[ketasuu//2:][::-1]))
    
    for i, (li, ri) in enumerate(zip(l, r)):
        if i == 0:
            add *= min(li, ri)
        else:
            add *= min(li, ri) + 1
else:
    if ketasuu == 1:
        add = int(s)
    else:
        l = list(map(int, s[:(ketasuu-1)//2]))
        r = list(map(int, s[(ketasuu+1)//2:]))
        
        for i, (li, ri) in enumerate(zip(l, r)):
            if i == 0:
                add *= min(li, ri)
            else:
                add *= min(li, ri) + 1

ans += add

print(ans)